Office systems such as printers and copiers require mechanical, electrical, and/or electromechanical assemblies for moving a print medium such as a paper sheet, a transparency, or other media such as magnetic or label transfer material, etc. (hereinafter, collectively, “paper”) through a paper path and ensuring that the paper is properly aligned for printing or copying. These assemblies may include an optical sensor having a light emitter that emits light to illuminate the paper path and a light detector that detects light reflected from or blocked by the paper path. System software and/or firmware (hereinafter, collectively, “software”) use information from the optical sensor to determine the presence or absence of a paper sheet in the paper path and, if present, a relative position of the paper within the paper path.
Light intensity output by the light emitter is calibrated for the particular office system design. The target light intensity should be sufficiently high so that the light detector correctly detects a paper sheet having a high percentage of dark printing. Further, the target light intensity should be sufficiently low to prevent reflection of light off of other machine elements in the absence of a paper sheet, which might be detected by the light detector and falsely interpreted by software as a paper sheet. Paper detection failure modes, including excessive and deficient light output by the light emitter, may also include contamination deposits on the optical sensor light path elements which may reduce light output by the emitter and light received by the detector, which adversely affects equipment operation. Additionally, component efficiency may degrade over time and reduce the detection of paper in the paper path. Contamination and reduction of component efficiency may require equipment servicing, and results in equipment down time and additional cost. Manufacturing tolerances on optical sensor components also affect the light output levels and resultant functionality.
An optical sensor that may overcome one or more deficiencies of conventional optical sensors would be desirable.